1. Field of the Invention
This invention relates to a linear vibration wave motor, and in particular to the structure thereof.
2. Description of the Prior Art
A vibration wave motor in which a travelling wave is generated in the surface of a vibration member having an electrostrictive element to thereby drive a movable member brought into contact with the vibration member is known from Japanese Laid-open Patent Application No. 148682/1983.
FIG. 1 of the accompanying drawings is a perspective view of a vibration wave motor for driving a movable member by a travelling wave generated in a vibration member, like the vibration wave motor disclosed in said patent application, and such motor has been proposed by the applicant.
The vibration wave motor shown in FIG. 1 is of the following structure. An electrostrictive element 4 is secured to an elliptical vibration member 1 supported by a support member 2 formed of felt or rubber, especially soft rubber. A periodic voltage is applied to the electrostrictive element to generate a wave in the vibration member, and a friction plate 9 is frictionally driven on the straight portion of the vibration member 1 by the travelling wave, whereby a movable member 3 connected to the friction plate 9 is driven in the directions of bilateral arrow through the friction plate 9.
However, the vibration wave motor shown in FIG. 1 is supported by the flexible support member 2 and therefore, the vibration member 1 is vibrated vertically and horizontally by the travelling wave generated in the vibration member 1 itself by the application of the voltage to the electrostrictive element. Alternatively when an extraneous force is applied to the driven movable member 3 for some reason or other, the movable member 3 vibrates vertically and horizontally because of the unstable support member 2, and this has led to a disadvantage that the movement locus of the movable member 3 does not exactly coincide with its predetermined locus and the movable member cannot be accurately driven.